Monday, July 26, 2010

Pictured is an optical micrograph of cells 24 hours after initiation of apoptosis. The image combines coherent anti-Stokes Raman scattering (CARS) microscopy and two-photon excited fluorescence (TPEF) to show spatial distributions of major biomolecules such as proteins (red), RNA (green), DNA (blue) and lipids (grey) during apoptosis. Here, proteins abandon the nucleolus, accumulating in a highly irregular distribution in the nucleoplasm, and genomic DNA condenses and partially segregates from the proteins. (from the cover page of PNAS, July 20.)

Arguably, the most celebrated phenomenon studied by biologists, the science of programmed cell-death or Apoptosis, is essential to normal development, healthy immune system function, cancer prevention and a plethora of other functions. The pace of investigation in this already deadly field would now surely hotten up with the monitoring of Real-Time Dynamics of apoptotic cells in Living Color.
New science featured on the cover of the current issue of PNAS, University at Buffalo (UB) scientists have developed a biophotonic imaging approach capable of monitoring in real-time, the transformations that cellular macromolecules undergo during programmed cell death.
To develop the know-how of efficiently capturing transient and high-resolution cellular images of the phenomenon, an interdisciplinary UB team of biologists, chemists and physicists, led by Paras N. Prasad, executive director of the UB Institute for Lasers, Photonics and Biophotonics, utilized an advanced biophotonic approach that combines three techniques: a nonlinear, optical imaging system CARS (Coherent anti-Stokes Raman scattering), TPEF (two-photon excited fluorescence), which images living tissue and cells at deep penetration and Fluorescence Recovery after Photobleaching (FRAP), to measure dynamics of proteins.
This approach allows one to to monitor in a single scan, four different types of images, characterizing the distribution of proteins, DNA, RNA and lipids, the 4 major macromolecules, in the cell. The resulting composite image integrates in one picture the information on all four types of biomolecules, with each type of molecule represented by a different color: proteins in red, RNA in green, DNA in blue and lipids in grey, as shown on the PNAS cover. This kind of Multiplex imaging provided new information on the rate at which proteins diffuse through the cell nucleus, the UB scientists say.
Researchers noted that before apoptosis was induced, the distribution of proteins in the cell was relatively uniform, but once apoptosis develops, nuclear structures disintegrate, the proteins become irregularly distributed and their diffusion rate slows down.
This ability of dynamic mapping of molecular transformations could potentially help realize the promise of customized molecular medicine, in which chemotherapy, for example, can be precisely targeted to cellular changes exhibited by individual patients. It can also be a valuable drug development tool for screening new compounds. With the increased understanding of cellular events at the molecular level, where one can clearly visualise the changing dynamics of DNA, RNA and lipids during the cell's disintegration, one could specifically use it for monitoring how specific cancer drugs affect individual cells.
The advancement in Biophotonic-tools to effectively investigate, and perhaps use it for predictive and therapeutic purposes has opened up the field of customized bio-medicine. Moreover, this could be employed towards the study of new fundamental cellular investigations and structural reorganization throughout the mitotic cell cycle.